Answer
Since we fail to reject the Null Hypothesis, there is not sufficient evidence that more than 40% of registered voters are Republicans.
Work Step by Step
$H_{o}$: p = 0.4, $H_{a}$: p > 1.4, n = 320, α = 0.05
1 - α = 0.95 , $z_{0.95} = 1.645$
p̂ = 142/320 = 0.4437
$z = \frac{0.4437 - 0.44}{\sqrt \frac{0.4 (1-0.4)}{320}} = \frac{0.0037}{0.0274} = 1.597$
Since 1.597 < 1.645, we fail to reject the Null Hypothesis.
